Much of the 3D buzz from CES was related to passive 3D HDTVs. And most of the action is around the film patterned retarder technology commercialized by LG Chemical and LG Display. Panels from LG Display will show up in 3D HDTVs from Vizio, Toshiba, Philips, LG Electronics and all six major Chinese TV brands. But there are two other approaches for creating passive polarized 3D HDTVs.

First, let’s clarify how we define a film patterned retarder. It is a film that is aligned and laminated to an LCD panel that provides polarization that is orthogonal on adjacent rows. That is, even rows are left circularly polarized and odd rows are right circularly polarized. 3D images are created from left and right eye image pairs by "interlacing" them into a single frame of video. Users wearing passive polarized glasses can separate the two images and see 3D. There is a loss of half the vertical resolution with this approach, however.

A second way to accomplish this is by using a glass sheet instead of a film sheet. Arisawa pioneered this technology and has been moderately successful with it in the professional market. However, the high cost has confined their approach to professional monitors.

AUO has recently developed a much less expensive way to do this on a glass substrate. It is currently supplying 65" panels to TV makers like Vizio.

The third major approach is an active polarization switch. When used with projectors, a large single-cell LCD panel rapidly switches the polarization state of the light coming out of the projector. RealD and Lightspeed Design produce polarization switching products that do this.

When the approach is applied to an LCD panel it is called a scanned or active retarder. In this case, the film or glass-based patterned retarder is replaced with an LCD panel. This panel can change polarization state by switching the voltage. To make this work in practice, the LCD panel is divided into a series of segments. Each segment is activated to change the polarization state in synchrony, with the scanning of the rows from top to bottom. The advantage of this approach is that there is no loss of resolution per eye in 3D mode. The downside is the cost of a second LCD panel.

Several companies are working on this approach. The most visible has been LG Display, which has been showing prototypes for over a year and a half. Initially, they’d hoped to commercialize this technology in 2011, but they have since pushed it out 1-2 years.

At CES, CPT was showing off its 15.6-inch 1366 x 768 active retarder type 3D display. Although it was shown installed in a laptop, the module size of 359.8 x 210 x 7.0 makes it a bit thick for a modern laptop display. The display looked great - there was no ghosting present in the images shown.

During CES, we also had a chance to see a new prototype developed by RealD and Samsung LCD in a suite at the Wynn. RealD calls its approach RDZ, and it uses 8 segments to create the polarization scanning. Demonstration units with screen sizes of 15", 17", 23" and 46" were developed. We saw the 46" demo and found it was quite good, with little ghosting.

The technology is clearly interesting, but the need to have an additional panel is a serious consideration. However, it does offer the performance of a shutter glasses 3D display with inexpensive glasses. If the cost of the scanning retarder panel can be kept to the cost of a pair of shutter glasses, then the approach might be viable.